Blister packages are used to pack a wide variety of products. Such packages usually inlcude a transparent plastic film bubble or blister secured to a stiff cardboard backing.
One common problem with blister packages is that they are often difficult to open manually, because the plastic blister and cardboard backing are not easy to tear.
There have been attempts to provide easy-to-open blister packages. For example, Hellstrom U.S. Pat. No. 3,942,640 shows a package having a blister secured about its entire periphery by an integral flange portion which is rigidly attached to a surface of a backing. The backing has an internal layer which is relatively frangible with respect to its other layers which are more resistant to tear. A pattern of score lines is cut in the backing beneath the flange of the blister. The score lines, which extend in depth between the surface of the backing and the frangible layer, promote tearing along the frangible layer when the blister is pulled away from the backing. Means are shown for grasping the blister, including a finger grip portion integrally molded in the flange of the blister.
However, Hellstrom is not readily adaptable to a user's established packaging format and existing stock of materials. Hellstrom requires backing having specific anisotropic strength characteristics. The backing must be carefully processed to provide a precisely cut pattern of score lines. New molds are required to form blisters having an integral finger grip on the flange, and these molds are very costly.
It would be desirable to provide an easy-to-open blister package which is readily adaptable to a user's current packaging stock without the need for format changes, substantial additional processing of materials, or costly mold revisions.